1. Field of the invention
The present invention relates to a reading unit mountable on a printing apparats, and a printing apparatus capable of mounting such reading unit thereon.
2. Related Background Art
The conventional printing apparatus is generally provided with a function to receive data from a computer and record them on a recording medium. In recent years, however, there has been a demand that the apparatus should be provided not only with such function as a printing apparatus, but also with a function to read the image data recorded on a recording medium as in a copying machine, facsimile equipment, or the like. A printing apparatus having a complex function of recording and reading is more in demand.
To comply with such demand, the printing apparatuses provided with the complex function are being developed. However, the conventional printing apparatus having reading means is such that recording means is mounted on a carriage that can hold such recording means, and that the recording means is replaced with recording means for reading images, or a method is adopted so that images are read by reading means as required, which is installed outside the printing apparatus.
For example, methods disclosed in Japanese Patent Publication No. 1-20832, Japanese Patent Publication No. 2-21711, and Japanese Patent Publication No. 2-21712, among others, are such that while sharing means for feeding a recording medium, the apparatus is arranged to make its head unit exchangeable so that it can be used for recording or reading.
Meanwhile, from the viewpoint of high-speed recording, quietness at the time of recording, smaller size and portability, an ink jet printing apparatus takes the lead among printing apparatuses available in recent years, because it can perform ink jet recording on a recording medium, such as a recording paper and a resin sheet, by use of an ink jet recording head as recording means. Also, of such ink jet printing apparatuses, the main current is the ink jet printing apparatus of a serial type wherein an ink jet recording head and ink tank are mounted on a carriage that reciprocates along a recording medium.
Now, even for such ink jet recording apparatus of the serial type, it has been desired that the apparatus should be able to perform ink jet recording, while it is provided with a function to read source documents. Here, as an actual method whereby to mount on an ink jet printing apparatus reading means provided with an image sensor or the like that optically reads images, it is possible to adopt a mode that enables reading means to be exchangeably mounted on an ink jet recording head or an ink jet recording head formed together with an ink tank, which can serve as recording means.
Nevertheless, the following problems are encountered in arranging such methods that reading means and ink jet recording means are exchangeably mounted on the apparatus:
(1) While reading means is mounted on a carriage carrier, the blade, cap, and others that serve as discharge recovery means for an ink jet recording head are in contact with the reading means. As a result, there is a fear that ink adheres to the light transmitting surface or other parts of optical path of the reading means. PA1 (2) The mounting of reading means on the carriage requires the transmission of large power and signals between the reading means and printing apparatus. This requirement inevitably invites the provision of flexible cable having a large capacitance for connecting the carriage and printing apparatus reliably. As a result, the resultant flexibility of the cable is lowered as a whole. Also, the space on the circumference of the carriage traveling area should be made larger inevitably. PA1 (3) Each time when recording is executed on a recording medium by use of reading means and ink jet recording means, and a source document is read by use of the reading means, extra operation and time are required to remove either one of the ink jet recording means and reading means from the carriage, and then, to mount the other one of them on the carriage.
Also, for the method whereby to install reading means outside the housing of a printing apparatus, there is a problem that the size of the printing apparatus becomes inevitably larger.